luckadjusted

Week 15 2021 · December 20, 2021

No FTN charting for this game (drops and interception-worthy throws are not modelled).

Vikings at Bears, Week 15 2021: who deserved to win?

The Vikings beat the Bears 17–9, but it was a coin flip: replayed with the way both teams played, the Vikings win 4 of 10. Luck ran their way: injuries alone were worth 5.6 points to the Vikings.

Before kickoff the Vikings were 70% favorites. The biggest swing (Q2, 0:59 left): the Vikings were stopped on 3rd & 8, worth 10 points of win probability to the Bears.

Final

Minnesota Vikings 17
Chicago Bears 9

December 20, 2021 · Soldier Field · Closing line: Vikings −7

Luck index +56 Vikings lucky · −56 Bears

Each team’s own plays from this game, resampled into new drives 4,000 times: with the way both teams actually played, how often does this performance win? How the replay works

Ten replays. Vikings win 4, Bears win 6.

  1. 1 MIN 31 CHI 10
  2. 2 MIN 26 CHI 14
  3. 3 MIN 27 CHI 20
  4. 4 MIN 18 CHI 16
  5. 5 MIN 19 CHI 21
  6. 6 MIN 6 CHI 10
  7. 7 MIN 26 CHI 34
  8. 8 MIN 17 CHI 29
  9. 9 MIN 24 CHI 40
  10. 10 MIN 10 CHI 36

Three other ways to ask

Each answers a different question, so none of them replaces the replay above.

The closing betting line, turned into a probability. What everyone knew before the game.

The line plus what this game showed, weighted by how much one game can tell. It stays close to the line because one game says little.

Every kick, fumble bounce, drop, conversion and judgment call redrawn; everything else fixed. The narrowest view of luck.

How 4,000 replays ended

Vikings win 44% of them, Bears 56%, counting the 2% still level after regulation as half each. The line is what actually happened: Vikings by 8.

Show as a table
Final margin in the replaysShare of replays
Vikings by 17+7.3%
Vikings by 9–1614.6%
Vikings by 1–819.5%
Level after regulation2.5%
Bears by 1–826.8%
Bears by 9–1616.8%
Bears by 17+12.7%

Where the luck was

Take the luck out

The final margin was Vikings by 8. Remove the luck, one kind at a time, and it becomes Bears by 11.9.

Each row takes one kind of luck out of the margin. Color shows which team it helped. Luck shares are the fitted ones (how much of each component is luck).

The kicks

How likely each kicker was to make that kick (his own record, the distance and the weather), and what happened.

  • G. Joseph, 37 yds made · 89% expected
  • C. Santos, 34 yds made · 92% expected
  • C. Santos, 49 yds blocked · 66% expected
Bar: expected chance of a make. Filled dot: made. Open dot: missed or blocked.

When it happened

Bears’ chance of winning

As low as 0% and as high as 61%. Numbers mark the biggest luck moments, listed below.

nflfastR’s in-game win probability. It ignores the betting line, so it starts near even. Shaded above the middle while the Bears were ahead in it, below while the Vikings were.
#WhenWhat happenedWin probability forNext drive
1 Q1 8:20 The Vikings converted 3rd & 83rd & 4th downs · 30% expected +10% MIN MIN: Touchdown
2 Q2 9:09 The Bears fumbled and the Vikings recoveredFumble bounces · loose balls are close to 50/50 +6% MIN CHI: Field goal
3 Q2 2:19 The Bears converted 4th & 13rd & 4th downs · 70% expected +7% CHI CHI: Field goal
4 Q2 1:21 The Vikings fumbled and recovered it themselvesFumble bounces · loose balls are close to 50/50 +7% MIN MIN: Turnover
5 Q2 0:59 The Vikings were stopped on 3rd & 83rd & 4th downs · 31% expected +10% CHI MIN: Turnover on downs
6 Q2 0:37 The Bears were stopped on 3rd & 23rd & 4th downs · 57% expected +8% MIN CHI: Missed field goal
7 Q2 0:33 C. Santos had a 49-yard field goal blockedKicks · 66% expected for him, 11 of 18 from 45+ before +8% MIN CHI: Punt
8 Q3 1:02 The Bears were stopped on 4th & 13rd & 4th downs · 70% expected +6% MIN CHI: Turnover on downs

Missing players

Key players (usually on the field for half the snaps or more) who missed this game or part of it, valued by position and quality. The same players are missing in every replay, so this counts as luck in points only.

  • Andy Dalton (CHI QB), out (IR), replaced by j.fields · 2.5 pts
  • Jaylon Johnson (CHI CB), out · 0.9 pts
  • Eddie Jackson (CHI SS), out (IR) · 0.8 pts
  • Allen Robinson (CHI WR), out (IR) · 0.7 pts
  • Jason Peters (CHI T), out · 0.6 pts
  • Khalil Mack (CHI LB), out (IR) · 0.6 pts
  • Larry Borom (CHI T), out (IR) · 0.5 pts
  • Tashaun Gipson (CHI FS), out · 0.4 pts
  • Artie Burns (CHI CB), out (IR) · 0.3 pts
  • Marquise Goodwin (CHI WR), out · 0.2 pts
  • Duke Shelley (CHI CB), out (IR) · 0.2 pts
  • DeAndre Houston-Carson (CHI FS), out · 0.2 pts
  • Everson Griffen (MIN DE), out (IR) · 0.9 pts
  • Danielle Hunter (MIN DE), out (IR) · 0.9 pts
  • Adam Thielen (MIN WR), out · 0.7 pts

Adjust the assumptions

Disagree with how much of a fumble bounce or a pass interference call is luck? Change it and the coin-flip replay reruns in your browser.

Only coin-flips re-rolled

Vikings 24% · Bears 76%

Final margin
Vikings by 8
Luck in points
19.9 for the Vikings
Luck-adjusted margin
Bears by 11.9
Replay with same day's form
Vikings 44% · Bears 56% unchanged: why
How much of each is luck?

0% treats it as skill, 100% as pure luck. The tick is our fit.

What counts

We tested momentum on 19,000 lucky breaks and found none, so it's off by default. Why

Flip a play

Force the other outcome, in this game and in every replay: a made kick becomes a miss, a stop becomes a conversion, a flag goes the other way.

About these numbers

Play-by-play and win probability from nflfastR via nflverse; kicks valued against each kicker’s own record; drops and interception-worthy throws from FTN charting (not available for this game); injuries from snap counts and injury reports. No FTN charting for this game (drops and interception-worthy throws are not modelled).

Methodology and validation · All Week 15 2021 games · Vikings · Bears

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